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An obvious prerequisite to caring for transplant recipients is a thorough understanding of immunosuppressive therapies [2]. Although acute rejection can occur at any time, the greatest risk is during the first 90 days after transplantation. Accordingly, immunosuppression is most intense during this time, and the chances of suffering its consequences are great (eg, drug toxicities, infection, and some malignancies [lymphoma]). In general, tapering to a less arduous regimen over time is done, with resulting reduction in the risks of toxicity and infection. With long-term survival, however, the duration rather than the intensity of immunosuppression becomes more critical and strongly influences the risks of other complications, including malignancies (skin), bone disease, and atherosclerosis.

Current maintenance immunosuppressive therapy involves multidrug regimens (including azathioprine or mycophenolate mofetil [MMF] and corticosteroids) built around a cornerstone, the calcineurin-inhibitor (either cyclosporine or tacrolimus) [2]. Therapeutic considerations in treating patients on either of the calcineurin inhibitors are remarkably similar in terms of both adverse effects and drug interactions (Figs. 13-1 and 13-2) [3-5]. Common azathioprine toxicities include bone marrow suppression and alopecia. Because azathioprine is metabolized by xanthine oxidase, concomitant use with allopurinol is problematic. MMF causes less bone marrow suppression than does azathioprine and does not interact with allopurinol, facilitating therapy of gout. However, gastrointestinal complaints (usually dose-related nausea, bloating, or diarrhea) are common. In addition, MMF may exacerbate the gastrointestinal toxicity of tacrolimus. Corticosteroid toxicities are well described; protocols designed to minimize corticosteroid exposure of transplantation recipients remain the ideal pursued by many physicians who treat these patients.